Immunogenicity is the capacity of an antigen to induce a cellular and/or humoral response. Immunopotentiation is the enhancement of such a response or the development of a response to an otherwise nonimmunogenic material. Agents that have the ability to so enhance or develop an immune response are called "adjuvants" or "immunopotentiators". Adjuvants are used to increase the efficacy of vaccines and in the treatment of immunity-associated diseases such as cancer, immunodeficiency, and certain infective diseases.
Many bacterial components have been investigated as immunopotentiators. Among these are components from a psycrophilic gliding bacterium of the genus Cytophaga. This Gram-negative bacterium was originally isolated from a contaminated lot (designated FBS 762) of fetal calf serum (FCS). Shiigi, S. M. and Mishell, R. I., J. Immunol (1975) 115:741-745. Medium conditioned by the growth of these gliding bacteria was found to have immunopotentiating activity on cultures of murine splenocytes supplemented with deficient FCS. Studies comparing the adjuvant and mitogenic effects of this medium with those of purified lipopolysaccharide (LPS) from S. typhosa indicated the activity of the medium was attributable to substances other than LPS from the gliding bacterium Shiigi, M. S. et al. J Immunol, (1977) 119:679-684. A further report regarding this bacterium describes the preparation of exopolymers (EP) from the medium in which the bacterium (then designated Cytophaga sp) had been cultured by dialysis and lyophilization. The Ep was characterized as being water soluble and containing .ltoreq.0.2% protein and .ltoreq.0.001% LPS. It was found to potentiate immune responses to specific antigens and stimulate murine macrophages and macrophage cell lines to release colony stimulating factors and interleukin 1 (IL-1). Mishell, R. I. et al, in Chemistry and Biological Activities of Bacterial Surface Amphiphiles, Eds Shockman G. D. and Wicken A. J., Academic press, New York (1981).